Gas producing charge



Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Mar. 7, 1955, Ser No. 492,801 18 Claims. (1. 149-96) This invention relates to the production of smokeless powders and more particularly to the production of smokeless powders having peculiarly desirable ballistics for applications in jet-actuated devices.

It is well known that there is a definite and direct relationship betweenthe pressure at which a smokeless powder propellant burns and its burning rate. This relation ship may be mathematically expressed as r=,cP or as log r=n log P log 0, where r is the burning rate, P is the pressure at which the burning rate is measured, and c and n are constants characteristic of a given propellant. Thus, when a plot of log r against log P is made for the conventional propellant, a straight line of slope n is obtained showing an increase in burning rate for each increase in pressure. Such a relationship is not disadvantageous in the conventional propellant and in fact is used to advantage in progressive powders where it is highly desirable to generate increased pressures after the projectile or shot charge has begun to move along the barrel.

* United States Patent However, this relationship presents a serious problem in formulation of propellants for jet-actuated devices since once the desired operating pressure is reached, totally different considerations obtai V v It is highly desirable, once the operating pressure of a jet-actuated device is reached, that the pressure generated by the burning propellant be maintained as nearly constant as possible. Accordingly, if this result is to be attained, the slope n of the line representing the pressure-burning rate relationship of the particular propellant "ice where AP is the experimental difference in pressure under PAt conditions of equilibrium burning due to the temperature change At; andl isthe mean of the low-temperature and high-temperature pressures.

The advantage of having a low-temperature coelficient of equilibrium pressure is obvious. If the coefiicient is low, the jet-actuated device may be designed for an unusually low range of service pressure over the wide temperature range ordinarily specified for such devices in field use. Since existing propellants generally have temperature coefficients of equilibrium pressure of about 0.8% C. or more, service pressure may change by 100% or more in going from the lowest expected temperature (about -60 -C.) to the highest expected temperature (about C.). It is therefore highly desirable to lower the temperature coefficient of equilibrium pressure below that of existing rocket propellants and thereby hold variation in service pres-sures due to temperature change to a minimum. If the coefiicient could be lowered from 0.8%/ C. to 0.4%/ C. or less, service pressure variation would be dhninished by at least one-half.

As a result of the advantages set forth above for a propellant having a low It value and a low temperature coefiicient of equili'briurn pressure, the combination of those two ballistic characteristics would allow additionally for important economies in the inert weight of jet-actuated devices. This is clearly seen if the equation is examined which relates the ratio between the mass of propellant (m) and the mass of the jet device without propellant (M the gas velocity of the burning propellant (V), and

must desirably approach zero in the zone of useful rocket pressure. In the prior art rocket powders, in all of which the slope n has a value of 0.7 or over, any fracturing or sllvering of the propellant charge leads to a pressure build-up because of an increase in linear burning rate resulting from the increase in pressure due to the increase in burning surface. The higher the n value of the particular powder, the higher will be the pressure rise encountered. Therefore, the results of such a fracturing or slivering vary from a highly undesirable thrust fluctuation, with consequent aberration in ballistics, to actual failure of the jet device if, with a propellant of high It Even unusual in the range of useful rocket pressures, however, would allow for considerable tolerances without appreciable deviation from the specified ballistics.

A second serious problem confronting producers of propellants for jet-actuated devices is the diminution of the temperature coeflicient of equilibrium pressure at the desired operating pressure or pressure range. The temperature coefiicient of equilibrium pressure is a. measure of the pressure variation tobe expected on account of temperature variation alone, using a given propellant. It

is obtained by firing identical samples of propellant under identical conditions except for changes in temperature and pressure. The coefiicient may be expressed as the highest theoretically obtainable velocity of the jet device (V as follows:

With propellants now available, the highest ratio of has been about 1, where mass of propellant and. mass of jet device are about equal. If it is possible, by use of a new propellant which will not build up excessive pressures, to decrease M by 10% and increase the amount of propellant to give the same total initial weight, V would be increased by a factor 1.1 lOgw (l i0g1 1 of about 1.15. This would be a 15% improvement.

Therefore, an object of the present invention is the production of propellants for jet-actuated devices which are characterized by such a burning rate-pressure relationship that substantially constant or more nearly constant burning rates are maintained throughout a wide pressure region within the range of useful rocket pressures.

It is a further object of this invention to produce a propellant for jet-actuated devices which is characterized by a lower temperature coeflicient of equilibrium pressure which will minimize variation of service pressure due to temperature.

Generally described, the present invention comprises gas producing compositions which comprise a smokeless powder having uniformly incorporated therein and intimately admixed therewith within every particle thereof not more than 10% of at least one aromatic compound of lead. The smokeless powders to which these ballistic modifiers are added may be of either single or multiple base. if the smokeless powder to which one or more of he varie a negative However, it is preferred to cm- In most cases it has been found ss powder employed is t of the additive to effect the desired given to illustrate specific formulad compound. Unless otherwise inr'enerally described the invention, the fol- 00000020 2 40 7 n51 201g A228 8 57 2 2 43983 8267 D I 000680550 4 51A 0 25 637(0 9 0- 6 11 32 9 3 l-fis usmn lfl lwwvn wm vmm 01m 761244n0 O 01 1 10 0000 0 199 0 D09 9 0 999999990188666088 8 818888 888008 m 111 111 1 11 L LL LLLl L L 1 1 1 L men Hw e t 1G 0 706701 1 6rd 2 6 11C) 0 16 1 83 4 0 5838 o bflzab 45 2 G 6 m 856657355 4 45 6 34 4 45 6 54m 4 45 3 6 2n0fd] 0111300634622 3 i n eimuw u s mtd m s GH GT C T we PM D.

t .00000 .0 0 00 .00 0000 0 000 O 00 n 0 OOOOOAUOOFOUOOOOOOO 5 000005 00000 2 .00000 .0 0 0O 00 0000 .D 050 0 00 O 0 005F000 0200 SOP/PU 7 90 77 5 0 est "20000 0 8 53 m 54 n -34 2 169 P r 7 8 d 7 up 33 3 m 444 a 4 a qaiiiqae 4 a medi 1 n O 000 0 0 O 0 0 0000 0 000 0 00 O 0 00000000 0 0000 00050 S 00O00 :7 0 05 0 O0 OOKUO O 000 0 0G 0 0 0 500 00 d 306 8% 00570 mw "P167055 "2 4 43 3 2A1 4234 5 4003 4 33 7 7 4 un SW51 12025 M n 2212 u 1 1F1 1 1 1 L l l l l l n 0019090144 6 58 6 Q2 A1976 6 381 0 0 6 5 06002004000 00000 0 376573 46755 W n nnz m hu u w a 4 43 4 4A) 4343 3 433 1 19 3 3 23000002100500420 3 243021 30141 0 1 B 2 2 C the ballistics of the gas-producing compo In fact, and as will be demonstrated, some of It has been found that up to 10% of t ble additives may be employed without adversemore than about 4% of the various additives,

g examples are Percent modifier 11 value. the aromatic lead compounds actually produc n value.

ous opera ly afiectin of a substantions of the invention.

Propellants ploy only sufficien modification in ballistics. e char that not ship having 10 based on the weight of the smokele ally lower usually ample. Morc- Having now lowin 2,802, tions in accordance with the invention and to compare hat by addisuch aowders to similar formulations whi h do not inthe clude the aromatic lea dicated, the powder compositions of the examples were prepared by the solvent process hereinafter described.

tron

erial No. 49

invention, which contain a he pressure region of low nitrocellulose, from 10 to of 5 sive plasticizer.

ount of the above-listed modifiers will b re coefiicicnt of equilibrium pressure. accordance with the invention disclosed and red according to this the ballistic modifiers is added is a single-base powder, it should preferably comprise from 85 to 95% nitrocellulose and from 5 to 15% plasticizer. If the propellant used is a multiple-base formula, it should preferably comprise from to explosive liq id ester, and from 5 to 30 tially nonvolatile nonexplo prepa minor am acterized by a pressure-burning rate rela a substantially lower 11 value and a substanti temperatu over, in

claimed in copending application S filed March 7, 1955, it has been discovered t tion of finely divided carbon to the compositions of present invention, the burning rate of the composition can be desirably increased in t See footnotes at end of table.

Temperature N Percent Pressure at coefficient Heat of Example 12.6% NG TA E0 NDPA Lead modifier modifier CB Low 11 low at p.s.i. of equilibexplosion,

Y N rium calJ/g.

pressure, percent/9 O.

58. 27 2, 5' Aminosalicylate 2 .10 1, 7703, 008 .50 850 58. 5 27 10 2.5 Oitr 2 1G 1, 520-3, 500 29 883 58. 5 27 8 2. 5 3-hydroxy-2-naphthoate 2 l0 1, 880-3, 050 28 858 fi-Resorcylate 2 v 58 5 7 8 2. 5 Salicylate 2 40 1, 270-1, 910 24 859 p-Hydroxybenzoate 2 95 l fi-Resorcylate 2 .5 860 Acetyl salicylate 2 1 Dinltrotoluene substituted [or nitrodipheuylamiue. 2 Pentaerythrltol trinitrate substituted for nitroglycerin. 3 Diethylphthalate substituted for triacetin.

N O'iE.--N C =nitrocellulose, N G =nitroglycerin, TA =triacetin, EC =ethyl centralite, N DPA =nitrodiphenylan1ine, OB =carbon black.

From the foregoing examples it is evident that although all of'the ballistic modifiers disclosed are operable, some are more effective than others in lowering the n value or the temperature coefiicient of equilibrium pressure of a given propellant. This fact allows for a wide choice of modifier based on economic considerations as Well as the ballistics desired for a particular application. From the combined viewpoints of elfectiveness and economy, lead 2,4-dihydroxy benzoate, lead salicylate and leadacetyl salicylate are preferred.

In copending application Serial No. 492,802, filed March 7, 195-5, it is disclosed that lowered n values and coefiicients of equilibrium pressure can also beobtained by incorporating lead, inorganic lead compounds or aliphatic lead compound in smokeless powder compositions having ahead of explosion not exceeding about 900 calories per gram. As illustrated in the examples, it may be desirable to employ a mixture of anaromatic lead compound and lead or nonaromatic lead compound. The use of mixtures of aromatic lead compounds with lead 2-ethyl hexoate are particularly desirable since lead Z-ethyl hexoate is a liquid and assists in obtaining the necessary uniform admixture of modifier throughout the composition. It has been noted, moreover, that especially where the heat of explosion of the composition does not exceed 900 calories per gram, the incorporation of lead or nonaromatic lead compound with the aromatic lead compound will often extend the pressure range of low 11 value in the low pressure direction. No more than 10% by weight of the mixture may be used.

The compositions of the invention may be prepared by solventless extrusion. In the conventional solventless process, water-wet nitrocellulose and the other ingredients are admixed in a Schrader bowl with water. The resulting slurry or paste is dried to tenpercent water and is colloided and dried between hot colloiding rolls which may be even speed or differential speed rolls as desired. The resulting colloided, dry sheets are then cut into disks or convolutely rolled into carpet rolls. The disks or carpet rolls are then extruded to desired grain size. Flake powder may be formed by suitably shredding the sheet. The resulting grains are normally glazed, usually with graphite, to lower static generation and to improve flowing characteristics.

The compositions of the invention may also be made by the solvent process. In the usual solvent process, the water in hydrated nitrocellulose is first replaced, for example, by treatment with ethyl alcohol. A colloiding solvent such as ether or acetone is then added to the dehydrated nitrocellulose along with additional ingredients and a doughy mass is formed in a suitable mixer such as Sigma blade mixer. This dough is then formed into green grains usually by extrusion into cords and cutting the cords to the desired length. The green grains are then subjected to solvent removal steps. The greater portion "of the solvent is normally removed by passing a warm inert gaseous medium such as air or flue gas over the only with extreme difiiculty. This diificulty increases as the web thickness is increased. It is therefore desirable to prepare grains of multiple-base formulations of this invention by solventless extrusion or by a suitable casting process. It 'is preferred to extrude grains up to about 5 or 6 inches in diameter and to cast all larger grains. Casting of the larger grains is preferred because the cost and massive nature of extrusion presses large enough to produce grains of over 5 or 6 inches in diameter become prohibitive.

, In the usual casting process, tiny singleor double-base powder grains, prepared by either the solvent or solventless techniques, are introduced into a mold together with suitable plasticizers. The plasticizers cause-the grains to coalesce into a unitary mass of plastic composition. The preferred casting process is that disclosed in thecopending application of Gordon W. McCurdy, Serial No. 28,218, filed May 20, 1948.

The single-base formulations given in the examples are preferably made by a conventional solvent process, ex-

. of the colloiding solvent.

truded and cut to the desired granulation. Such a process eter or web thickness which will allow sufiicient removal Grains of solvent-colloided powder having large diameter and web are of course operable and addition of the disclosed modifiers according to this invention will effect the desired modification in ballistics. It is of course well known that the change in ballistics during storage caused by gradual migration and evaporation of the colloiding solvent is the reason why large grains of solvent-colloided powder are not manufactured. As improved processes and means for solvent removal are developed, it will perhaps be possible to produce correspondingly larger grains of solvent-colloided powder which are ballistically stable.

It is not preferred to produce single-base grains by solventless extrusion or by casting because, in order to keep the powder in the single-base category, the plasticizer employed to bring about colloiding and/or consolidation must be of lower potential than the nitrocellulose. The necessary amount of plasticizer, therefore, so lowers the potential that such powders have only a limited application. Nevertheless, incorporation of the disclosed modifiers in single-base grains prepared by solventless extrusion or by casting still results in a low n value and a lowtemperature coefficient of equilibrium pressure.

If the gas-producing charges of this invention are made by solventless extrusion, the ballistic modifier or modifiers are preferably added at some time prior to dehydration of the water slurry and the additive system is mixed to a state of homogeneity. The slurry is then dehydrated, the moist mass is rolled into colloided sheets, the sheets are made into rolls and the rolls are extruded in the conventional manner. However, it is often found advantageous to add the ballistic modifiers during the rolling operation, rather than to the water slurry. The modifiers are then intimately admixed throughout the composition by action of the rolls. If the well known Schrader process is employed, the modifiers may be added to the hydrated nitrocellulose in the mixing bowl in any preferred order. A portion of the water is evaporated prior to rolling. The Schrader process is preferred when watersoluble plasticizers are employed.

If the charges of this invention are prepared by solvent extrusion, the ballistic modifier or modifiers are preferably added to the dehydrated nitrocellulose after it has been broken up in a mixer. The modifiers may be introduced with the plasticizer or plasticizers or may be added before or after introduction of the plasticizer as may be desired in the particular formulation.

If the grains are made by casting, the ballistic modifier is homogeneously incorporated during the preparation of the casting powder as above described.

In order to produce the plateau type ballistics of the invention, the modifiers must be uniformly incorporated with the other ingredients of the composition; that is, the modifier must be intimately admixed with the other ingredients within each particle of the composition whether the charge is a loose charge of individual grains or consists of a single grain of any desired size. The glazing or coating of a single grain or a plurality of grains in a loose charge will not produce the desired modification in the pressure-burning rate relationships. Thus, powder grains coated or glazed with a lead compound to render them free-flowing are not operable in the invention.

The heat of explosion of an explosive composition may be experimentally determined in the known manner by actually exploding a sample of the substance in a bomb calorimeter under conditions which insure complete combustion of the constituents of the composition, and measuring the heat liberated. However, in the case of smokeless powder compositions which contain at most only small portions of inorganic material, it is usually desirable to determine the heat of explosion by calculation. The calculation of heats of explosion is especially desirable in order to predetermine the calorific value of a proposed composition prior to its formulation. In this calculation, use is made of a simple relation; namely, the heat of explosion per gram of powder is equivalent to the sum of the products of the weight fraction of a given constituent by the contribution to the heat of explosion of the constituent. This contribution of the constituent is for convenience termed the partial calorific potential or the partial heat of explosion, and is usually designated as K Thus, the heat of explosion of the composition is derived by the equation:

Heat of explosion=2X K,

where X, is the weight fraction of the powder component i.

For compositions consisting principally of carbon, hydrogen, oxygen and nitrogen, K is quickly and accurately determined according to the following equations:

where O, is the number of gram-atoms of oxygen per gram of the powder component i, C, is the number of gram-atoms of carbon per gram of the powder component i, H, is the number of gram-atoms of hydrogen per gram of the powder component i, RC. is the heat of combustion at 25 C. and constant volume, and

ABA is the heat of formation per gram of the powder component i from its elements.

Partial heats of explosion for inorganic substances such as the ballistic modifiers of the invention are not quite so easily calculated by may be determined according to methods disclosed by De Pauw in Z.f.ges. Schiessund Sprengstoffwesen, 32, ll, 36, 60 (1937); or by Hirschfelder and Sherman in Simple Calculation of Thermochemical Properties for Use in Ballistics, O.S.R.D. Report No. 1300, declassified and issued as P13274213.

Actually, it is unnecessary to experimentally determine the K values for the various constituents of the smokeless powders in accordance with the invention since tables of the partial heats of explosion for these materials are available as published data. The following is a listing of the K; values of the normally used smokeless powder components and many of the operable ballistic modifiers in accordance with the invention.

Partial heat of Substance (i) explosion (cal./ g.)

Acetone 1938 Carbon black 3330 Diamylphthalate 2190 Dibutylphthalate 2055 Diethanol nitramine dinitrate +1294 Diethylene glycol dinitrate +1030 Diethylphthalate -1746 Ninitrotoluene Diphenylamine 2684 Diphenylurea 2227 Diphenylurethane 2739 Ethyl alcohol -1749 Ethyl centralite -2398 Ethyl urethane +1639 Graphite 3377 Lead 0 Lead acetate 282 Lead phthalate acetate 462 Lead diacetylacetonate 868 Lead anthranilate --864 Lead azide +365 Lead benzoate 950 Lead m-aminobenzoate 796 Lead dichlorobenzoate 736 Lead 2,4-dimethoxybenzoate 766 Lead 2-ethy1hexoate -1336 Lead 4-ethoxy-Z-hydroxybenzoate 870 Lead p-hydroxybenzoate 826 Lead bromide -l37 Lead carbonate (basic) 471 Lead chloride -151 Lead chromate +977 Lead citrazinate 752 Lead tetraethyl 1725 Lead fluoride -127 Lead gallate -573 Lead gentisate 674 Lead hydroxide --189 Lead iodide -91 Lead linoleate 1982 Lead pyromellitate 250 Lead trimesate 460 Lead molybdate +403 Lead tetrachloronaphthalate 534 Lead naphthenate -2048 Lead l-hydroxy-Z-naphthoate -1ll7 Lead 3-hydroxy-2-naphthoate -1l17 Lead oleate 2010 Lead oxalate +58 Lead oxide (PbO) +67 Lead oxide (Pb O +139 Lead oxide (PbO +302 Lead n-butylphthalate -974 Lead [B-resorcylate 704 Partial heat of Substance (i): explosion (caL/g.) Lead tetraphenyl -l725 Lead salicylate -752 Lead acetylsalicylate -857 Lead aminosalicylate 746 7 Lead thiosalicylate +874 Lead stearate -2800 Lead phthalate stearate 1543 Lead sulfate --l50 Lead sulfide '-222 Lead tartrate 172 Lead o-toluate -10 57 Nitrocellulose 13.25% N +1041 13.15% N +1027 13.00% N +1007 12.60% N +951 12.20% N +895 12.00% N +867 11.50% N +797 7 Nitroglycerin +1735 Nitroguanidine +720 Triacetin ---1284 Water n value or a negative n value is obtained. Although particular emphasis has been placed on the desirability and advantages of the compositions of this invention when applied to jet-actuated devices, it is to be understood that these compositions have a general utility in applications where gas-producing charges are desired. They are especially advantageous where substantially constant pressures are desired and where any rapid increase in pressure would be highly undesirable.

This application is a continuation-in-part of my copending application Serial No. 102,427, filed June 30, 1949, now abandoned.

What I claim and desire to protect by Letters Patent is:

l. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of at least one aromatic compound of lead and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

2. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead 2,4-dihydroxy benzoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

3. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead salicylate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

4. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereofan amount not exceeding 10% of lead,

acetyl salicylate and said composition having a value of 1 less than 0.7 for the slope n of the line representing the pressure-burning rate relationship. I

5. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of a mix-- ture of lead salicylate and lead 2-ethyl hexoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate re-' lationship.

.6. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of a mixture of lead acetyl salicylate and lead Z-ethyl hexoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

7. A gas-producing composition consisting essentially of a smokeless powder containing to of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof not. more than 10% of at least one aromatic compound of lead and said composition having a value of less than 0.7 for the slope n of the line representingthe pressureburning rate relationship.

8. A gas-producing composition consisting essentially of a smokeless powder containing 85% to 95 of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof not more than 10% of lead 2,4-dihydroxy benzoate and said composition having a value of less than 0.7 for the' slope n of the line representing the pressure-burning rate relationship.

9. A gas-producing composition consisting essentially of a smokeless powder containing 85% to 95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof not more thon 10% of lead acetyl salicylate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

10. A, gas-producing composition consisting essentially of a smokeless powder containing 85% to 95 of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof not more than 10% of lead acetyl salicylate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

11. A gas-producing composition consisting essentially of a smokeless powder containing 85% to 95 of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof not more than 10% of a mixture of lead salicylate and lead Z-ethyl hexoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

12. A gas-producing composition consisting essentially of a smokeless powder containing 85% to 95 of nitrocellulose and having uniformly. incorporated therein and intimately admixed therewith within each particle thereof not more than 10% of a mixture of lead acetyl salicylate and lead Z-ethyl hexoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

13. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith not more than 10% of an aromatic compound of lead and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

14. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith not more than 10% of lead 2,4-dihydroxy benzoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

15. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith not more than 10% of lead salicylate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

16. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly in corporated therein and intimately admixed therewith not more than 10% of lead acetyl salicylate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

17. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly in- '12; corporated'therein and intimately admixed therewith not more than 10% of a mixture of, lead salicylate and lead 2-ethyl hexoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

18. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith not more than 10% of a mixture 01" lead acetyl salicylate and lead 2-eth l hexoate and said composition having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

References Cited in the file of this patent UNITED STATES PATENTS 1,357,865 Henning Nov. 2, 1920 2,385,135 Holmes Sept. 18, 1945 2,498,388 Ball Apr. 14, 1950 2,982,638 Cooley May 2, 1961 FOREIGN PATENTS 621,685 Great Britain Apr. 14, 1949 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,033,715 May B 1962 Ralph E. Preckel It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 34 for "compound" read compounds column 8 line 5, for "by" read but column 10 line 39 for 'thon" read than same line 39 strike out "acetyl'h Signed and sealed this 4th day of September 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A GAS-PRODUCING COMPOSITION CONSISTING ESSENTIALLY OF A SMOKELESS POWDER HAVING UNIFORMLY INCORPORATED THEREIN AND INTIMATELY ADMIXED THEREWITH WITHIN EACH PARTICLE THEREOF AN AMOUNT NOT EXCEEDING 10% OF AT LEAST ONE AROMATIC COMPOUND OF LEAD AND SAID COMPOSITION HAVING A VALUE OF LESS THAN 0.7 FOR THE SLOPE N OF THE LINE REPRESENTING THE PRESSURE-BURNING RATE RELATIONSHIP. 